atlases & charts

Atlas Coelestis

John Flamsteed
London, 1729
Atlas of 27 double maps
From the Special Collections of the University of Michigan Shapiro Science Library

Flamsteed’s Atlas Coelestis is one of the “big four” star atlases to come out of Europe’s Golden Age of celestial cartography, a period which spanned roughly 1600 to 1800 and which was driven by technological advances in astronomical observation and printing techniques. This group also includes the Uranometria of Johann Bayer (1603), the Firmamentum Sobiescianum sive Uranographia of Johannes Hevelius (1690), and the Uranographia of Johann Elert Bode (1801). Many other notable atlases were produced during this period, such as Johann Doppelmayr’s Atlas Coelestis and the Harmonia Macrocosmica of Andreas Cellarius.1

While Flamsteed’s is so far the only one of the “big four” star atlases to have been photographed for this exhibit, it is a good choice, for when it appeared it set a new standard in accuracy and completeness: It contained far more stars than previous atlases, utilized a very precise grid, and its star positions were based on telescopic observations which Flamsteed had painstakingly checked and re-checked over the course of his 43-year career as the first Astronomer Royal of England.2

John Flamsteed (1946-1719) was a self-taught astronomer who came to the attention of the Royal Society in 1670 after corresponding with British scientists, including Sir Jonas Moore (1627-1679). In 1675, with Moore’s help, Flamsteed convinced Charles II to construct the first Royal Observatory at Greenwich to address the problem of British ships getting lost at sea due to inaccurate star catalogs (which were used to calculate longitude). Charles appointed Flamsteed Astronomer Royal; he took up residence at the Royal Observatory in 1676 and began to compile a new star catalog based entirely on telescopic observations, a task that occupied him until his death in 1719. It is this catalog (sometimes referred to as the British or Britannic catalog) that formed the basis of Flamsteed’s Atlas Coelestis. The final version of Flamsteed’s star catalog was published in 1725 by his widow and former assistants; the atlas was published in 1729.3

Its 27 maps, including two double maps, are drawn from a geocentric perspective and are titled according to their most prominent constellations. In addition there is a pair of celestial hemispheres which are 50.6 cm in diameter. Unlike Bayer’s Uranometria, which had created a precedent for mixing frontal and rear depictions of the constellation figures, Flamsteed revived the Ptolemaic convention of drawing them all frontally, a feature which he claimed was a major advantage over Bayer’s atlas.4

The Atlas Coelestis was heralded as an immensely useful achievement, but there were problems too: the constellations Cerberus, Crater, and half of Hydra were omitted,5 the volume’s size made it unwieldy, and the artistic quality of the constellation figures did not compare favorably with the great star atlases of the past. Ashworth is characteristic in his assessment of Flamsteed’s achievement:

The Flamsteed atlas was welcomed because of its unprecedented accuracy, but it did suffer from some deficiencies. It was, for one thing, almost too big to use, with its 24 by 20 inch plates. It also lacks the aesthetic quality of both the Bayer and Hevelius atlases. While Andromeda is graceful enough, Aquarius is almost grotesque, especially when compared with the artful Aquarius in Bayer’s Uranometria.6

Flamsteed’s atlas marks a transition away from the star atlas as artistic work and toward the featureless star charts of the 19th and 20th centuries. The telescope had allowed astronomers to see more of the universe than ever before; already the stars cataloged by Flamsteed were so numerous that his maps were not completed until fourteen years after his death. The original mnemonic function of the constellations was beginning to lose its relevance, and the artistic qualities of the printed figures were downplayed in favor of completeness and positional accuracy. Although constellation figures would remain on professional star maps well into the 19th century, they had begun a process of wasting slowly away, and would eventually be relegated to popular astronomy texts while professional astronomers did away with them entirely.